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Free · Private · Works in your browser
YouTube Thumbnail Checker
Check thumbnail size, preview real YouTube layouts, and improve mobile readability before you publish.
Size & format check
Multi-layout preview
Mobile readability
Safe-zone check
Check a thumbnail
Preview before publishing
Check up to three thumbnails
Upload your designs, add video details, and compare how each version looks across YouTube.
1
Upload thumbnails
JPG, PNG or GIF · Up to 3 images
2
Video information
Add context for realistic previews
Use M:SS or H:MM:SS
3
Check & preview
See technical checks and layouts
Images stay on your device
Technical checkSize, ratio, format
Layout previewHome, Search, Suggested, Mobile
Visibility testsTiny, Blur, Gray, Dim, Safe zone
Compare versionsUp to three designs
Privacy firstLocal browser processing
Technical check
Thumbnail readiness
Each result includes a clear next step.
Layout preview
See it where viewers browse
Switch layouts and visibility tests instantly.
Side-by-side
Compare thumbnail versions
Review every version at the same display size.
Made for publishing decisions
Everything needed for a strong pre-publish check
Technical confidence
Review dimensions, aspect ratio, format, and file-size readiness for desktop and mobile uploads.
Real browsing context
Preview the same design in Home, Search, Suggested Videos, and a compact mobile feed.
Fast visual checks
Use tiny, blur, grayscale, dim, and safe-zone views to reveal readability and placement issues.
How it works
From upload to decision in three steps
- 1
Upload one to three designs
Your browser reads the image dimensions, format, and file size locally.
- 2
Add your title and duration
The preview uses your video details to recreate a realistic YouTube card.
- 3
Preview, test, and compare
Switch layouts and visibility modes, then refine the version that communicates most clearly.
FAQ
YouTube thumbnail checker questions
What does the thumbnail checker review?
It reviews image format, dimensions, 16:9 aspect ratio, file size, mobile readability, safe areas, and appearance in common YouTube layouts.
Are uploaded thumbnails sent to a server?
No. The image is read and displayed locally by your browser, so the design stays on your device.
Can I compare multiple thumbnail versions?
Yes. Upload up to three designs to compare them at the same display size with matching video details.
Does the tool work on phones?
Yes. The checker is responsive and supports image upload, technical checks, layout previews, and comparison on mobile devices.